Atomic Structure and the Periodic Table

Question 1

What are atoms made up of?

Answer 1

Protons, neutrons and electrons

Question 2

Give the relative mass and relative charge of each subatomic particle?

Answer 2

Particle | Mass | Charge
Proton | 1 | +1
Neutron | 1 | 0
Electron | 1/1840 | -1

Question 3

What is the relative isotopic mass?

Answer 3

The mass of an atom of an isotope comapred with 1/12th the mass of a carbon-12 atom. RIM is an isotopes mass number

Question 4

What is the relative atomic mass?

Answer 4

The ratio of the average mass of an atom of an element to 1/12th of the mass of an atom of carbon-12

Question 5

What is relative molecular mass?

Answer 5

The ratio of the average mass of a molecule of an element or compount to 1/12th of the mass of an atom of carbon-12

Question 5

What is relative molecular mass?

Answer 5

The ratio of the average mass of a molecule of an element or compount to 1/12th of the mass of an atom of carbon-12

Question 6

What is relative molecular mass?

Answer 6

The ratio of the average mass of a molecule of an element or compound to 1/12th of the mass of an atom of carbon-12

Question 7

What is the relative formula mass?

Answer 7

The average mass of a formula unit of a substance, relative to 1/12th the mass of a carbon-12 atom.

Question 8

What is the mass number of an element? How is it represented?

Answer 8

A - The total number of protons and neutrons in the nucleus

Question 9

What is the atomic (proton) number of an element? How is it represented?

Answer 9

Z - The total number of protons in the nucleus

Question 10

What is an isotope?

Answer 10

Atoms with the same number of protons and different numbers of neutrons.

Question 11

Describe the process of mass spectrometry.

Answer 11

Vapourisation - turning the sample into a vapour
Ionisation - an electron gun is used to displace electrons from all the vapourised atoms which gives them all a 1+ charge
Acceleration - charged atoms are accelerated in an electric field
Deflection - a magnetic field is used to deflect the charged atoms; the amount a particle is deflected depends on its mass
Detector - particles with less deflection have a higher mass

Question 12

What can you determine from the data produced in mass spectrometry of a sample?

Answer 12

You can find the relative abundances of different isotopes on an element. RMM of each species in a sample is shown on the x axis. Relative atomic mass can also be calculated from the data, using relative isotopic masses and abundances.

Question 13

What are the four types of orbitals and how many electrons it can hold? (In order of ascending electron capacity)

Answer 13

s-2,p-6,d-10,f-14

Question 14

What is meant by the term orbital?

Answer 14

A region of space within an atom that can hold up to two electrons with opposite spins

Question 15

Describe an explain existing evidence for the existence of quantum shells and sub-shells.

Answer 15

Atomic emission spectra and successive ionisation energies prove the existence of quantum shells.
First ionisation energy of sucessive elements proves the exisence of electron sub-shells

Question 16

What are the three rules that are used when filling shells and sub-shells with electrons?

Answer 16

Afubau’s rule - fill shells from lowest to highest energy (4s is lower than 3d)
Pauli’s rule - electrons in the same orbital must have opposite spin
Hund’s rule - fill orbitals in the same group individually before pairing

Question 17

What are the two exceptions to Afubau’s rule of filling lower energy shells first?

Answer 17

Copper and chromium should only have one electron in the 4s orbital, not 2 and then other electron goes into the 3d orbital.

Question 18

Define first ionisation energy.

Answer 18

Energy required to
remove 1 electron each from
1 mole of gaseous atoms

Question 19

Define second ionisation energy.

Answer 19

Energy required to
remove 1 electron each from
1 mole of gaseous 1+ ions.

Question 20

Write an equation to represent the first ionisation energy.

Answer 20

C(g) -> C+(g) + e-

Question 21

Write an equation to represent the second ionisation energy.

Answer 21

C+(g) -> C 2+(g) + e-

Question 22

What factors affect the ionsation energy of an atom? How do they affect it?

Answer 22

Nuclear charge - more charge, more energy required
Distance and shielding from nucleus - greater distance/shielding, less energy required
If the outermost electron is sharing an orbital - ?

Question 23

Describe and explain the change in ionisation energy across a period.

Answer 23

IE increases due to:
- increasing nuclear charge
- attraction to nucleus increases

NB.
- distance + shielding remains relatively constant

Question 24

Describe and explain the cahnge in first ionisation energy down a group.

Answer 24

First IE decreases down the group:
- despite the increase in nuclear charge
- distance/shielding increases more significantly
- overall decreasing the attraction to the nucleus

Question 25

Describe and explain the trend of atomic radii across different periods.

Answer 25

Down group:
- increases as more shells of electrons fill

Across period:
- decreases (despite increase in no. of e-) due to increasing nuclear charge

Question 26

Describe and explain the trend of ionic charge across different periods.

Answer 26

Metals loose e-
Non-metals gain e-
Ionic charge depends on group.

Question 27

Describe and explain the trend of ionic radii across different periods.

Answer 27

Increase down the group due to increasing no. of shells of electrons.
Decrease across period as ions isoelectronic with an increasing nuclear charge.

Question 28

Describe and explain the trend of structure and bonding across different periods.

Answer 28

Group 8/0 - monatomic
Metals (G1-3) - giant : metallic
Non-metals (G4) - giant : covalent
Non-metals (G5-7) - simple : covalent

Question 29

Describe and explain the trend of electrical confuctivity across different periods.

Answer 29

Metals have delocalise electrons in pure structure which can conduct a current.
All others have no available charge carriers (electrons) in pure structure.

Question 30

Define periodicity.

Answer 30

Trends in properties of elements (and their atoms) repeat in successive periods of the periodic table.